John Hancock vs signature

John Hancock and signature both are nouns.

Word	Noun	Adjective	Verb	Adverb
John Hancock	Yes	No	No	No
signature	Yes	No	No	No

As nouns, signature is a hypernym of John Hancock; that is, signature is a word with a broader meaning than John Hancock:

John Hancock (noun)	signature (noun)
a person's own signature	a distinguishing style
American revolutionary patriot who was president of the Continental Congress; was the first signer of the Declaration of Independence (1737-1793)	your name written in your own handwriting
	a sheet with several pages printed on it; it folds to page size and is bound with other signatures to form a book
	the sharps or flats that follow the clef and indicate the key
	a melody used to identify a performer or a dance band or radio/tv program